2-thiocyanoethyl phenylcarbanilates



United States Patent Z-THIO CY AN OETHYL PHENYLCARBANILATES David T. Mowry, Kirkwood, Mo., and Arthur H. Schlesinger, Dayton, Ohio, assignors to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware No Drawing. Application May 27, 1953, Serial No. 357,884

3 Claims. (Cl. 260-454) The present invention relates to carbanilates and more particularly provides new and valuable esters of phenylcarbanilic acid and methods of preparing the same.

According to the invention there are prepared phenylcarbanilates having the formula Nncooomcfim in which R is selected from the class consisting of -Cl, -Br and -SCN. Compounds having the above formula and provided by the invention are the 2-chloroethyl, 2- bromoethyl or Z-thiocyanoethyl esters of 2-, 3- or 4- phenylcarbanilic acid. The 2-chlo1'oethyl phenylcarbanilates are valuable as stable high-boiling plasticizers for vinyl polymers. Both the 2-chloroethyl and the 2- bromoethyl phenylcarbanilates are readily converted, by reaction with an alkali metal or ammonium thiocyanate, into the Z-thiocyanoethyl phenylcarbanilates, which compounds possess insect-repellant properties.

The present haloethyl phenylcarbanilates are obtained by reaction of the appropriate haloethyl haloformate with o, m, or p-xenylamine, substantially according to the scheme:

Q nm+xoooorncrny QNELCOOCHQOIBY HX in which X and Y are selected from the class consisting of chlorine and bromine. Reaction of the haloformate with the amine takes place very easily, generally, by simply mixing the two reactants, in the presence or absence of a basic agent as catalyst. Initial contact of the haloformate with the xenylamine, particularly in the presence of a catalyst, results in evolution of reaction heat. Hence in order to effect a smooth reaction, it is generally advisable to operate in the presence of an inert diluent or solvent, e. g., benzene, hexane, nitrobenzene, dioxane, etc. When using a diluent, after the initial exothermic reaction has subsided, it may be necessary to apply external heat in order to assure complete reaction within a practical period of time.

Conversion of the haloethyl phenylcarbanilates to the thiocyanoethyl compounds is conducted by contacting the haloethyl phenylcarbanilate with the inorganic thiocyanate at ordinary or increased temperatures; however, for optimum yields of the thiocyanoethyl phenylcarbanilates, it is preferred to heat a mixture of the haloethyl compound and the inorganic thiocyanate, advantageously in the presence of an inert solvent or diluent, at a temperature of from say, 60 C. to the refluxing temperature of the reaction mixture until conversion of all of the haloethyl compound into the thiocyanoethyl 70 2,786,071 Patented Man-19, 1957 as methanol, ethanol, isopropyl alcohol, acetone, ethyl acetate and isopropyl ether; nitro compounds such as the nitroparafiins and nitrobenzene, etc. In order to facilitate removal of the inorganic halide which is formed 5 as a by-product, it is preferred to employ as a diluent a liquid in which the halide is substantially insoluble;

"ice

hence, an alcoholic or ketonic diluent is generally pre ferred.

Inasmuch as the condensation involves one mole of 0 the haloethyl phenylcarbanilate with one mole of the inorganic thiocyanate, stoichiometric proportions of the reactants are advantageously employed. However, since any excess of either the halide or the thiocyanate may be readily removed from the final product, the quantity of reactants initially employed is immaterial. It is preferred, however, to use an excess of the more readily available inorganic thiocyanate in order to assure complete reaction of the haloethyl compound under the reaction conditions employed. Inorganic thiocyanates which may be employed include potassium, sodium,

lithium, barium, calcium, strontium, magnesium and ammonium thiocyanates.

The 2-thiocyanoethyl phenylcarbanilates are stable,

rather high-boiling materials having a pleasant aromatic 5 odor. They are particularly valuable as insect repellants, but also may be advantageously employed as rubber-compounding chemicals, and as intermediates in the production of other industrially important raw materials. The invention is further illustrated, but not limited,

by the following examples:

Example 1 This example describes the preparation of 2-chloroethyl 2-phenylcarbanilate. A mixture consisting of 40.0 g. (0.276 mole) of 2- aminobiphenyl, 21.8 g. (0.276 mole) of pyridine, 39.4 g. (0.276 mole) of 2-chloroethyl chloroformate and 400 ml. of benzene was allowed to reflux for one hour. The reaction mixture was then permitted to cool, washed with water and allowed to stratify. The resulting benzene layer was washed with dilute hydrochloric acid, then with dilute aqueous sodium carbonate and finally with water. Removal of the benzene from the washed layer by distillation in vacuo gave a red syrup which did not crystallize upon standing. It was admixed with 85 percent ethanol and benzene, and the water, ethanol and benzene were stripped in vacuo from the resulting mixture to give 60.1 g. of a crude, red, residual oil. A 30.0 g. portion of this crude oil was re-distilled to yield 26.5 g. of the substantially pure 2-chloroethyl Z-phenylcarbanilate, B. P. l94-196 C./3 mm., 11 1.5955, and analyzing as follows:

The 2-chloroethyl 2-phenylcarbanilate, B. P. 194-196 C./3 mm., of Example 1 was converted to Z-thiocyanoethyl 2 phenylcarbanilate by employing the following procedure:

A mixture of 19.5 g. (0.0775 mole) of the 2-chloroethyl compound, 8.0 g. of potassium thiocyanate, 800 ml. of ethanol and a crystal of potassium iodide was refluxed for 114 hours. Filtration of the cooled reaction mixture gave 5.2 g. of potassium chloride (theoretical, 5.8 g.). The alcohol was removed from the filtrate by distillation in vacuo, and water was added to the residue. The oil layer which separated was removed and the aqueous layer washed with chloroform. The combined chloroform washings and the oil layer were vacuum dried to give 12.8. (61%) yield of the substantially pure 2-thiocyanoethyl 2-phenylcarbanilate, a clear, yellow oil.

The haloethyl Z-phenylcarbanilates and the preparation thereof froma xenylamine and a haloethyl haloformation form the subject of my copending application Serial No. 563,854, filed February 7, 1956.

What we claim is:

1. The method which comprises contacting a haloethyl phenylcarbanilate in which the halogen substituent is selected from the class consisting of chlorine and bromine, with an inorganic thiocyanate selected from the class consisting of alkali metal and ammonium thic- References Cited in the file of this patent UNITED STATES PATENTS 2,562,948 Robbins et al. Aug. 7, 1951 2,573,973 Johnson et a1; Nov. 6, 1951 2,642,456 Emerson et al. June 16, 1953 2,653,163

Jacob Sept. 22, 1953 

3. 2-THIOCYANOETHYL 2-PHENYLCARBANILATE. 